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Check Probe Connection

Verify probe cable connection at the machine connector and ensure probe wire is connected to Skip Signal input on the control.

Power down spindle before handling probe connections

Test Probe Signal

Go to CURRENT COMMANDS screen and manually activate probe while watching Skip Signal status change from OFF to ON.

The Skip Signal should toggle immediately when probe tip is pressed

Inspect Cable Integrity

Check probe cable for damage, especially at cable chain entry points and spindle connection areas.

Replace damaged cables immediately to prevent intermittent failures

Verify Parameter 31

Check Parameter 31 (Skip Signal) is set correctly - typically set to 1 for normally open probe configuration.

Parameter 31 = 0 for normally closed, Parameter 31 = 1 for normally open probes

Verify Workpiece Position

Check that workpiece is properly positioned and secured in expected location relative to program coordinates.

Use manual jog to verify probe can physically reach the intended surface

Review G31 Programming

Examine G31 probe move distance in program to ensure it's sufficient to reach workpiece surface with safety margin.

Ensure probe move doesn't exceed machine travel limits

Check Work Coordinate System

Verify correct work offset (G54-G59) is active and properly set using WORK COORDINATE menu.

Use G31 with incremental moves (G91) for more predictable probe distances

Test Probe Approach

Run probe cycle in single step mode to observe probe movement and verify it approaches workpiece correctly.

Use reduced feedrate for initial testing to prevent probe damage

Visual Inspection

Inspect probe body and stylus for physical damage, bent stylus, or loose connections at probe body.

Handle probe carefully - stylus and internal mechanisms are precision components

Manual Activation Test

Manually deflect probe stylus while monitoring Skip Signal on CURRENT COMMANDS screen to verify internal switching.

Probe should activate with light pressure - excessive force indicates internal damage

Check Probe LED Indicator

If probe has LED indicator, verify it illuminates when stylus is deflected, indicating internal electronics are functioning.

LED behavior varies by probe model - consult probe manufacturer documentation

Stylus Replacement Test

Replace stylus assembly if damaged or worn, ensuring proper torque specification and thread engagement.

Use only manufacturer-approved stylus assemblies to maintain probe accuracy

Verify Parameter 31

Check Parameter 31 (Skip Signal) matches probe type - set to 1 for normally open, 0 for normally closed probe configuration.

Most touch probes are normally open and require Parameter 31 = 1

Check Parameter 32

Verify Parameter 32 (Skip Signal Input) is set to correct input number corresponding to probe connection.

Incorrect input assignment will prevent probe signal recognition

Review Macro Variables

Check macro variables #5061-#5065 for probe results from previous cycles that may indicate parameter issues.

Macro variable #5067 indicates if last probe cycle was successful (1) or failed (0)

Parameter Backup and Reset

If parameters appear corrupted, restore from known good backup or reset probe-related parameters to default values.

Always backup current parameters before making changes

Check Grounding

Verify probe cable shield is properly grounded and machine electrical ground connections are secure.

Poor grounding is the most common source of probe signal interference

Test with Spindle Off

Perform probe test with spindle stopped to determine if spindle motor is source of electrical interference.

If probe works with spindle off, investigate spindle grounding and cable routing

Cable Routing Inspection

Ensure probe cable is routed away from power cables and uses separate cable chain compartment if available.

Maintain minimum 6-inch separation between probe signal cables and motor power cables

Filter Installation

Install signal filter or ferrite core on probe cable if interference persists after other corrections.

Consult Haas service before adding filters that may affect probe response time